Modern electronic mobile devices of today utilize earpiece devices with microphones mounted on the outer side of earspeakers. For example, such products are used as active noise cancelling systems and binaural microphone systems for recording. Earpiece mounted microphones may also be used for sending voice in a voice call. Utilizing ear mount microphones solely saves money due to the removal of one dedicated voice microphone.
Further, there are design advantages. A more compact design is achieved without a separate cord mounted voice microphone. Further, an ear piece mounted microphone is positioned relatively fixed in comparation to a cord mounted microphone. This may be advantageous when applying noise suppressing algorithms.
Algorithms and methods for background noise suppression by the use of earpiece mounted microphones are known. Since the earspeaker and the microphone are mounted in the same earpiece device, there will be an acoustic coupling from the earspeaker to the microphone. In a voice call this will be perceived as an acoustic echo experienced by the far end user. Normally this echo is small, due to good fit between the ear piece and the ear channel, hence high attenuation from received voice to the sent voice is achieved.
If, however, one earpiece falls out of the ear, or if the user only has only one of the earpieces inserted, there will instead be a strong echo from the received voice transmitted by the earspeaker to the sent voice transmitted by the microphone. This will give a very unpleasant voice echo in the device at the far end of a voice call.
Still further, the voice echo need to comply with the requirements in 3GPP 26.131-“Acoustic echo control in a headset UE”.